轧制差厚板纵向弯曲回弹规律分析

为了推动轧制差厚板在汽车梁结构件上的应用，以U型件为对象，研究了轧制差厚板的纵向弯曲回弹特性。首先完成了差厚板U型零件纵向弯曲成形数值模拟，分析了差厚板的回弹趋势，讨论了差厚板的应力分布，揭示了差厚板弯曲回弹规律，探讨了差厚板等效应力的影响因素，并通过试验对回弹仿真结果进行验证。结果表明，不均匀的应力分布是纵向弯曲的差厚板U型件沿弯曲轴方向上回弹不一致的根本原因，退火处理能够减小差厚板卸载前后的应力差，从而实现抑制差厚板回弹的作用。差厚板的板料尺寸、厚度、过渡区长度均会对差厚板的等效应力造成较大影响，从而改变差厚板的回弹大小及分布。另外，差厚板零件不同厚度部位的回弹相互牵制，使得各部分的回弹量趋向一致，从而导致差厚板的回弹量均介于薄、厚等厚板之间。

Analysis on bending springback law of tailor #br# rolled blank in longitudinal bending

 In order to promote the application of Tailor Rolled Blank (TRB) in the structural parts for auto beams, the bending springback characteristics of TRB in the longitudinal bending process were studied by taking U channel as a research object. Firstly, the numerical simulations on the longitudinal bending process of TRB U channel were performed. The bending springback trend of TRB was analyzed, and the stress distribution of TRB was discussed. The bending springback law of TRB was revealed, and the influencing factors of TRB equivalent stress were discussed. Moreover, the springback simulation results were verified by the corresponding experiments. The research findings showed that a non uniform stress distribution was the fundamental reason why there was an uneven bending springback distribution in the direction of the bending axis during the longitudinal bending process of TRB U channel. Annealing can diminish the stress difference of TRB before and after unloading, thus restricting the TRB bending springback. All of the blank size, the blank thickness and the thickness transition zone (TTZ) length of TRB will greatly affect the equivalent stress of TRB, and then change the bending springback value and distribution. Besides, the bending springback of different zones with varying thicknesses in a TRB part interact was mutually restrained, which made the TRB springback tend consistent, resulting in the TRB bending springback lay between the springback of the thinner and thicker plates.